1. Field of the Disclosure
This disclosure generally relates to a touch sensing device and, more particularly, to a multipoint positioning method for a touchpad capable of detecting the multi-touch operation.
2. Description of the Related Art
As the touch control can be performed easily and without using conventional extra peripheral devices, such as the mouse or keyboard, it has gradually been applied to various portable electronic products, wherein single-touch technology has become mature but multi-touch technology still has the problem of unable to distinguish multiple fingers in some specific conditions in both capacitive touch panels or optical touch panels, especially in the condition that more than two fingers are very close to each other.
U.S. Pat. No. 5,825,352, entitled “Multiple Fingers Contact Sensing Method for Emulating Mouse Buttons and Mouse Operations on a Touch Sensor Pad”, discloses a sensing method for identifying multiple fingers according to one-dimensional information. The sensing method retrieves one-dimensional information at first as shown in FIG. 1A, and then respectively identifies a first peak P1, a valley V1 and a second peak P2 in the one-dimensional information. Next, a first finger area and a second finger area are separated according to the valley V1. Then, a finger position of the first finger area is obtained by calculating a first centroid of the first finger area, and a finger position of the second finger area is obtained by calculating a second centroid of the second finger area to divide different fingers. However, this method has to identify the valley V1 at first and then two finger areas can be separated accordingly.
As shown in FIG. 1B, when a second peak P2′ is significantly larger than a first peak P1′, using a valley V1′ to separate a first finger area and a second finger area may cause the asymmetry of the separated finger areas. When the centroid is used to locate the finger position, the finger position can have deviation such that the control error may occur.
Accordingly, the present disclosure further provides a multipoint positioning method for a touchpad that may simplify and increase the accuracy of the multipoint positioning procedure.